Hitherto, as a device for positioning a fastening member with respect to a fastened member, there is known such an apparatus which comprises a detector formed by a chucking claw of an automatic screw fastening machine mounted on a tip end of a movable element of a robot the detector having a plurality of detecting elements formed by each of light receiving end faces of plural optical fibers dispersed in a given arrangement on a tip end face of the chucking claw, and a position correcting control means for correcting positional displacement between the tip end of the automatic screw fastening machine and a screw hole by detecting a light transmitted by each of the optical fibers (for example, see Patent Document 1).
Patent Document 1: Japanese patent application publication No. S58-206387.